When it comes to Wisconsin's race for the U.S. Senate, Illinois businessman Richard Uihlein has not been shy about spending his cash to get Kevin Nicholson across the finish line in the Republican primary.

On Thursday, the Uihlein-backed Solutions for Wisconsin group unleashed a $911,000 television buy that will be up in several markets through the Tuesday primary.

In all, Uihlein-supported groups have spent $10.7 million on the race in support of Nicholson and against his rival, Leah Vukmir, according to Republican and Democratic operatives tracking media placements.

The latest ad targets Vukmir for derisive comments she made about Donald Trump in March 2016. Vukmir later endorsed Trump and campaigned for his election.

Uihlein is a founder of Pleasant Praire-based Uline Corp. He and his wife, Elizabeth, are the top individual contributors nationally to races in the current campaign cycle. They have contributed $30.4 million to support Republicans and conservatives, according to the Center for Responsive Politics.

According to the center's website, OpenSecrets.org, outside groups and the three candidates — Vukmir, Nicholson and Democratic U.S. Sen. Tammy Baldwin — have combined to spend $36.9 million so far, the most in the nation. That figure does not include the latest Uihlein buy.

Wisconsin's spending has been turbocharged by the GOP primary. Other Senate races in Florida, Texas, Missouri and Tennessee will likely surpass Wisconsin's spending in the general election.

Since winning election in 2012, Baldwin has raised $21.5 million, far more than her GOP rivals. Nicholson has raised $3.3 million and Vukmir has raised $2 million.

Vukmir has also received support from Wisconsin Next PAC, which has spent $2.5 million on ads supporting her candidacy and against Nicholson's.

That group has received $1.5 million from Diane Hendricks, chairman of Beloit-based ABC Supply Co. The Metropolitan Milwaukee Association of Commerce has also contributed $1.1 million to Wisconsin Next.

"We don't comment on the specifics of our political giving," said Steve Bass, senior vice president of governmental affairs for MMAC. "All the donations we make are fully disclosed in accordance with the relevant federal and state election laws."